Dataset of the article 'Spectroelectrochemistry of water oxidation kinetics in molecular versus heterogeneous oxide iridium electrocatalysts'

Dataset of the article 'Spectroelectrochemistry of Water Oxidation Kinetics in Molecular versus Heterogeneous Oxide Iridium Electrocatalysts',  https://doi.org/10.1021/jacs.2c02006.

Abstract: Water oxidation is the step limiting the efficiency of electrocatalytic hydrogen production from water. Spectroelectrochemical analyzes are employed to make a direct comparison of water oxidation reaction kinetics between a molecular catalyst, the dimeric iridium catalyst [Ir₂(pyalc)₂(H₂O)₄-(µ-O)]²⁺ (Ir_Molecular, pyalc = 2-(2’pyridinyl)-2-propanolate) immobilized on a mesoporous indium tin oxide (ITO) substrate, with that of an heterogenous electrocatalyst, an amorphous hydrous iridium (IrO_x) film. For both systems, four analogous redox states were detected, with the formation of Ir(4+)-Ir(5+) being the potential-determining step in both cases. However, the two systems exhibit distinct water oxidation reaction kinetics, with potential-independent first-order kinetics for Ir_Molecular contrasting with potential-dependent kinetics for IrO_x. This is attributed to water oxidation on the heterogenous catalyst requiring co-operative effects between neighboring oxidized Ir centers. The ability of Ir_Molecular to drive water oxidation without such co-operative effects is explained by the specific coordination environment around its Ir centers. These distinctions between molecular and heterogenous reaction kinetics are shown to explain the differences observed in their water oxidation electrocatalytic performance under different potential conditions.